Method for making abrasive articles and apparatus therefor



Re. 22,419 j Jan. 11, 1944. I J, 5. SMYSER METHOD FOR MAKING ABRASIVEARTICLES AND APPARATUS THEREFOR Original Filed Feb. '7, 1924 2Sheets-Sheet 1 Jan, 11, 1944. gMYsER Re. 22,419

METHOD FOR MAKING ABRASIVE ARTICLES AND APPARATUS THEREFOR OriginalFiled Feb. '7, 1924 2 Sheets-Sheet 2IIIYIIIII/III!IIIIIIIIIIIMIIIllIIIIIfl/I a IIII/IIIIIMMIIIMIIIIIIIIIIIIIIIIIIIIII/IIMIIII/III/III/IIIfl/IIII/Ill Reissued Jan. ll,

ME'EHUD AEiTtASlWE ARTICEES AME: APPfiQRfihfiS .laines El. Eniyscr,liioston, lliiass assignor to llilinn'esota lfrianuiac iuring C0111-pany, St. Paul, Minn a corporation of labels,-

(El. ill-d7) Claims.

strips or sheets of fabric, paper or the like with abrasive particles ashereinafter described in connection with illustrative embodiment.

Objects of my invention are to provide a sine-- pie, and efficientmethod of producing an abra sive surface on a fabric or other articleserving as a base, without materially affecting the flexibility orstrength of the article; to provide an electrostatic method ofcontinuously, and progressively producing an abrasive coating on a sheetof fabric, or other article, as it is moved in substantially thedirection oi its surface; to provide an improved coated fabric or otherarticle; and generally to provide an improved method of and apparatusfor producing an abrasive coating on an article.

In one aspect my invention contemplates electrostatically applying anabrasive coating to a fabric, or other article serving as a base, byelectrostatlcally projecting abrasive particles into engagement orbinding contact with the article being coated, and then forcing theengaged par- "ticles into more intimate engagement with the article..

In another aspect, an abrasive coating is electrostatically applied toan electrically non-conducting article by providing a conducting pathextending over the article, applying a coating of binding material tothe article, and bombarding the last applied coating by a stream ofabrasive particles electrostatically charged oppositely to theconducting path of the article.

In still another aspect, the invention provides a fabric or otherarticle coated with a conducting material having a superposed coating01' binder material upon which there is deposited a coating of granularmaterial.

The article, when in sheet form, may be coated by moving the sheetcontinuously in substantially the direction of its surface; dipping aportion oi the sheet into a liquid bath having comrninuted conductingmaterial in suspension, to coat the sheet; drying the liquid from thecoating to leave a conducting path over the surface of the sheet; makinga sliding contact between the conducting portion of the sheet and oneterminal of a source of electromotive force; dipping the sheet in aliquid bath of binding material to leave a coating of the binder on thesheet; equalizing the distribution of the'blnder coating on the sheet;moving the sheet through a stream of abrasive particles which areelectrostatically charged by the source of electromotive force with asign opposite to that of the conducting path of the sheet; equalizingthe distribution of abrasive particles over the surface of the sheet,and forcing the particles into more intimate engagement with the sheet.

Methods and apparatus illustrating a species, of which my invention is agenus, are described more fully hereinafter in connection with theaccompanying drawings, in which:

Fig. l is an elevation, in section cally showing apparatus for preparingan abrasive coating on a sheet of fabric;

Fig. 2 is a plan of a portion of Fig. 1;

Fig. 3 is an enlarged view of a portion of Fig. 1;

Figs. i, 5, 6 and 7 are cross sections of a fabric in successive stages,respectively, of the coating operations.

In Fig. 1 the sheet A of fabric, paper, or similar of its surface anddirected by rollers so that it passes continuously through a series ofzones B, C, D and E, in each one of which the sheet is subjected to adifferent operation.

The sheet A feeds from the roll ID in the direction indicated by thearrow into the coating zone B where it passes around rollers H, and dipsinto the liquid bath l2 in tank I3, the liquid having in suspensiongranular or comminuted graphite or other conducting material. The liquidis preferably non-corrosive and without appreciable physical or chemicaleffect upon the sheet when used primarily to suspend the conductingparticles; it may be water or other suitable liquid. The sheet passesbetween the rollers M which remove the excess of the mixture from thesheet, resulting in a substantially uniform distribution of conductingmaterial throughout. The rollers it direct the sheet through a dryingzone C within the chamber [6, having a heating element ll, such as asteam pipe, or other heater. The liquid upon drying from the coating onthe sheet leaves the conducting material distributed over the surface asa conducting path. The brush it in contact with the sheet is connectedtothe positive terminal of the source of electromotlve force l9 whichelectrifies the conducting path of the sheet with a charge of positivesign.

Rollers 26 direct the sheet through the zone D, in which, a coating ofbinding material is applied to the sheet as it dips into the liquidbath2| of binding material, such as parafiimor other sult' diagrammatiablebinder, preferably electrically non-conducting, in tank 22, heated by asteam pipe (not shown), or other suitable means. The rollers 2| removethe excess liquid and distribute the coat ing uniformly over the surfaceto equalize its thickness.

In the zone E, a coating of abrasive is electrostatlcally applied to thesheet. The hoppers 30 for containing abrasive particles of emery,carborundum, pumice, or other suitable abrasive material having the sizeof particle with which it is desired to coat the sheet, dischargethrough spouts 3| into the cylindrical electrifying chambars 32,preferably of electrically insulating material, disposed on oppositesides of the upwardly moving sheet. The nozzles 33 discharge air intothe conduits 34 (see Fig. 3), these conduits having apertures 38 whichadmit the moving air at suitable pressure to the abrasive container 40to produce a condition in which the abrasive particles are temporarilysuspended in the atmosphere of the container into which the particlesenter through orifices 38 into the zone of the electrical discharge,which takes place between the needles 31 mounted on bus-bars 33 and theconducting sheet.

Bus bars 36 are connected preferably to the negative terminal of sourceof electromotlve force l9 by means of leads 39, the effective potentialof the source l9 being adjusted to such a value, e. g. 18,000 volts,more or less, than the abrasive particles in chamber 32 becomeelectrifled with a negative charge, and together with the air admittedthrough nozzle 33 discharge through slot 38 as a stream of electrifiedparticles which are electrostatically propelled toward the positivelycharged sheet A, the solid particles bombarding and coming intoengagement with the binder coating on the sheet. Itwill be seen that theelectrostatically propelled abrasive particles emerging from each of theorifices 38 be-- come deposited as a thin blanket on the sheet A as itpasses through the discharge zone.

The housing 40 for apparatus in the zone E prevents loss of the abrasiveparticles which fail to become attached to the sheet A, a.nd ispreferably constructed of insulating material. Conduit 4! is connectedto an exhaust pump (not shown) and exhausts air from the housing it inthe direction indicated by the arrow, the end of conduit; 4| beingcovered by a screen 62 which sifts the abrasive particles from the airbefore entering the conduit. Air free from abrasive particles isadmitted through openings 43, and 45, thus tending to clarify the airwithin the housing and together with the air discharged through slots 38causing a flow of the air and drift of the abrasive particles around.the ballle diaphragms 46 as indicated by the arrows, the bafilestending to cause a precipitation of the particles at one end of thehousing as indicated by the accumulation 41 which also includes theabrasive sifted by the screen 32. Owing to the reduced air pressure inhousing flfl when air is exhausted through conduit 4|, air may be fedthrough nozzles 33 directly from the atmosphere, but if a greater flowis desired compressed air may be fed through these nozzles.

Rollers 48 between which the sheet passes, after being coated with theabrasive, equalizes the distribution of abrasive material on the surfaceof the sheet and forces the abrasive particles into more intimateengagement with the sheet which then passes upward and is wound on theroll 49. The sheet may be propelled by rotation of the roll 49 or one ormore of the rollers with which the sheet contactsbetween rolls l 0 and'49.

Figure 4 shows the appearance of a simple fabric sheet A, ofelectrically insulating or poorly conducting material, having a warp 50and a woof 5|, before the sheet has entered the coating zone B. Fig. 5shows the particles 52 of graphite or other conductor distributed overthe surface of the fabric after the liquid from the batch l2 has i Byvirtue of the electrostatic charges upon the abrasive particles as theypass to the fabric they are held apart by electrostatic repulsion andconsequently are distributed far more eifectively than is possiblewithout the use of an electrostatic field. Thus the abrasive materialmay be deposited in any degree of depth, from an extremely, thin depositapproximately one particle thick to a thick deposit, and in any case theparticles are distributed with great uniformity. By coating the fabricupon both sides its usefulness is practically doubled and by virtue ofthe roughness of the rear side the article can be used more effectivelywith less danger of slippage in the fingers.

While certain materials have been mentioned in disclosing an example ofhow the invention may be carried out, it is to be understood that thematerials specifically named are not necessary to the invention but maybe replaced by other suitable materials. It is obvious that the sheetmay be treated in the various zones B, C, D and E by variousmodifications of the apparatus disclosed within the knowledge of thoseskilled in the art.

The method, and apparatus disclosed for carrying out the method, permitof producing an abrasive coating on sheet fabric or other articles,

particularly those in which it is desired to provide a certain degree oielasticity or flexibility, without objectionably stiffening the sheet orotherwise materially aifecting those properties of the sheet which it isdesired to preserve.

Owing to the more commonly elongated nature of abrasive particles, theytend to align themselves in the electrical field and are thus projectedor bombarded against the adhesive coating with their longer dimensionperpendicular thereto, thus permitting a nesting of the particles withrespect to each other in the adhesive coating. Furthermore this permitsof the adhesive coating exercising its capillary attraction,

so that it will more readily rise along the sides of each individualabrasive particle and catch and hold additional particles subsequentlyapplied before setting of the adhesive,

One of the inherent characteristics of the article produced by theimproved method and apparatus disclosed herein resides in the fact thata major portion of the abrasive particles embed themselves in theadhesive coating and assume positions with their greater dimensionsperpendicular or substantially perpendicular to the plane, of thecarrier, that is a sheet of fabric or paper as I the case may be. Thus Iam enabled to provide article known to me. I have, therefore, provided anew article of manufacture wherein the cutting edges or points of theabrasive particles are presented toward the surface to be abraded andmaterially enhance the efficiency of the abrasive article such asincreasing its cutting ability and as well as its ability to keep clean.

I have found my improved method and apparatus peculiarly useful for theproduction of abrasive articles in view of the further followingconsiderations. Abrasive particles present relatively sharper points oredges and, likewise, relatively less sharp portions. Where the particlesare given an electrostatic charge, the density of thecharge is greaterat the points or edges than on any relatively more or less flat part ofthe surface of the particle. For this reason, the particle projectedelectrostatically aligns itself so that the sharpest point or edgepoints in thedirection of the electrostatic field as it arrives at theadhesive coated surface. Inasmuch as I direct the electrostatic field Iemploy so that it acts perpendicularly to the surface coated with theadhesive, the particle acted upon so attaches itself to the adhesivesurface as to present its sharpest cutting edge or pointoutwardly of thesurface and in the direction of the electric field.

I am thereby enabled to produce an abrasive coating of extraordinarysharpness even with particles which are not necessarily markedlyelongated, as well as when I employ the more common abrasive particlesof an elongated contour. Thus I am enabled to attain an alignment ofparticles by means of an electrical field which affords a surface coatedabrasive presenting the greate'st'number and most effective cuttingpoints and edges known to me and one characterized by extraordinarycutting ability.

In the claims where I have referred to the abrasive particles beingdispersed with major effectiveness for abrasively coating said backing,I mean to include the result produced in depositing grit or abrasiveparticles under the influence of an electrical field such as anelectrostatic field to whicheffect I attribute a tendency to anorientation, positioning or displacement of the abrasive particles withthe longer axes more or less perpendicular to the backing.

Reference is made to my divisional application Serial No. 640,978, filedNov. 3, 1932, for

Abrasive articles, wherein the article is claimed.

I claim: I

1. Apparatus for applying coatings to electrically non-conducting sheetmaterial, comprising means for feeding thesheet in substantially thedirection of its surface, means for coating the moving sheet with aconducting material, means for applying a coating of binder materialover said conducting coating, and means for electrostatically bombardingthe binder coating with electrically charged particles to produce acoating upon said binder coating.

2. Apparatus for applying coatings to electrically non-conducting sheetmaterial, comprising means for propelling the sheet substantially in thedirection of its surface, means for applying to the sheet a coating ofliquid having conducting particles in suspension, means for drying theliquid to leave conducting particles as a coating on the sheet, meansfor applying a coating of binder material to the sheet, and means forelectrically projecting a stream of granular matter into engagement withthe binder coating to apply a superficial coating to the sheet.

3. The method of electrostatically depositing a coating upon an articlecomprising agitating granular matter in the presence of an electricfield, confining movements of the agitated particles' to a restrictedzone, and electrostatlcally projecting the electrified particlesoutwardly from f 1 the restricted zone to the object to be coated.

4. The method of preparing an abrasive coating on fabric or similarmaterial, which comprises continuously moving the sheet in substantiallythe direction of its surface, progressively dipping the sheet in aliquid bath having finely divided conducting material in suspension,drying up the liquid left as a coating on the sheet and leaving thesuspended particles deposited on the sheet to form a conducting pathover the surface of the sheet, coating the sheet with a binder,equalizing the thickness of the binder coating, electrostaticallyprojecting a stream of abrasive particles against the sheet, and forcingthe abrasive particles into closer engagement with the sheet.

5. The method of preparing an abrasive coat ing on a sheet of fabric orsimilar material, which comprises moving'the sheet substantially in thedirection of its surface, dipping the sheet in a liquid. bath havingcomminuted conducting material in suspension, drying up the liquid leftas a f coating on the sheet and leaving the suspended material depositedto form a conducting path over the surface of the sheet, dipping thesheet in a bath of liquid binding material, and electrostaticallydepositing a coating of abrasive particles on the binder.

6. The method of preparing an abrasive coating on a sheet of fabric orsimilar material, which comprises passing the sheet through a liquidhaving comminuted conducting material in suspension, withdrawing thesheet from the liquid and drying the liquid to leave a coating ofconducting material on the sheet, coating the sheet with a bindingmaterial, and electrostatically projecting abrasive particles intoengagement with the coating of binding material.

'7. The method of preparing 'an abrasive coat- I ing on a sheet offabric or similar material, which comprises coating the sheet with anelectrically conducting material electrostatically projecting abrasiveparticles into engagement with the sheet and forcing the engagedabrasive particles into more intimate engagement with the sheet.

8. The method of preparing an abrasive coating on a sheet of fabric orsimilar material, which comprises continuously moving the sheet insubstantially the direction of its surface, Progressively coating thsheet with a liquid having comminuted conducting material in suspension,progressively drying the liquid to leave the suspended material as aconductive coating on the sheet, progressively coating the sheet with abinding material, and progressively bombarding the sheet with a streamof abrasive particles electrically charged oppositely to the conductingcoating of the sheet.

9. The method of preparing an abrasive coatelectrified oppositely to theconducting coating into engagement with the sheet. and securing theengaged abrasive particles into more intimate engagement with the sheet.

10. The method of preparing an abrasive coat-.

ing on an electrically non-conducting base, which comprises coating thebase with an electrically conducting material, coating the conductingmaterial with a. binding material, and electrostatioally projecting astream of abrasive particles into engagement with the binder coating.

11. The method of making an abrasive article which comprises rendering asheet of fabric or the like both conductive and adhesive and byppositely charging the conductive sheet and comminuted abrasiv materialadjacent thereto, electrostetically depositing a layer of said materialupon the adhesive surface thereof.

12. The method of coating a sheet of material with abrasive particleswhich comprises rendering the sheet both conductive and adhesive and, byoppositely charging the conductive sheet and abrasive particles in theregion of the sheet, electrostatically depositing the abrasive particlesupon the adhesive surface of the sheet.

13. The method of coating a sheet of material with abrasive particleswhich comprises rendering the sheet both conductive and adhesive,continuously agitating a supply of abrasive particles in an enclosedregion, continuously feeding the sheet along a path associated with saidregion, and by oppositely charging the conductiv sheet and abrasiveparticles in said region electrostatically embedding the particles uponthe adhesive surface of the sheet.

14. Apparatus for applying adhesive material to an electricallyconducting surface and depositing thereon finely divided particles underthe influence of an electrostatic field, comprising means for moving thesurface in substantially the direction of its length, means for applyingadhesive material to the surface, and means for electrostaticallybombarding the adhesive material with electrically charged particles toproduce a coating upon said adhesive material.

15. Apparatus for applying finely divided particles to a surfacepreviously rendered electrically conducting and adhesive, comprisingmeans for producing an electrostatic field in a region containing finelydivided particles and means for moving the surface through saidelectrostatic field.

16. The method of electrostatically depositing finely divided materialparticles upon an article, which comprises establishing an electrostaticfield, dispersing the finely divided material particles to form asuspension in a region containing the electrostatic field, confiningmovements of said particles to a restricted zone and electrostaticallyprojecting them to the article to be coated.

17. The method of spreading an abrasive coating on a sheet of fabric orsimilar material which comprises treating the sheet to render itelectrically conductive and mechanically adhesive, establishing anelectrostatic field of force between the .surface to be coated and acharged conductor of opposite polarity to that of the sheet and adjacentthereto, conveying finely divided abrasive particles into theelectrostatic field of force and moving the surface progressively and insubstantially its own plane through the electrostatic field of forcewhereby the abrasiveparticles may, by the action of the electrostaticfield of force upon them, be deposited thereon.

18. The method of spreading a coating of finely divided particles .on asheet of fabric or similar material which comprises treating the sheetto render it electrically conductive and mechanically adhesive,establishing an electrostatic field of force between the surface to becoated and a charged conductor of opposite polarity to that of the sheetand adjacent thereto, conveying the finely divided particles into theelectrostatic field of force, and moving the surface progressively andin substantially its own plane through the electrostatic field of forcewhereby the finely divided particles may, by the action of theelectrostatic field of force upon them, be deposited thereon.

19. Apparatus for depositing finely divided v particles on the surfaceof a. fabric or other 1 material comprising means for treating thefabric to render it electrically conductive and mechanically adhesive,means for establishing an electrostatic field of force between twoelectrodes of opposite polarity one of which is in electrical contactwith the surface of the fabric, means for conveying the finely dividedparticles into the electrostatic field of force where, under itsinfluence, they will be deposited on the surfaceof the fabric, and meansfor progressively moving said surface in substantially the direction ofits length.

20. Apparatus for depositing finely divided abrasive particles on thesurface of a fabric or other material comprising means for treating thefabric to render it electrically conductive and mechanically adhesive,means for establishing an electrostatic field of force between twoelectrodes of opposite polarity one of which is in electrical contactwith the surface of the fabric,

means for conveying the finely divided abrasive particles into theelectrostatic field of force where, under its influence, they will bedeposited of which it will be translated to the surface to I be coated,and subjecting successive parts of the surface to the combined action ofthe electrostatic field of force and the pulverized material in a mannerthat will be substantially continuous.

22. The method of coating, with finely divided abrasive material, asurface that is both electrically conductive and mechanically adhesivecomprising establishing an electrostatic field of force between twoelectrodes of opposite polarity one of which is in electrical contactwith the surface to be coated, conveying the finely divided abrasivematerial into the electrostatic field of force under the action of whichit will be translated to the surface to be coated, and subjectingsuccessive parts of the surface to the combined action of theelectrostatic field of force and the finely divided abrasive material ina manner that will be substantially continuous.

23. The method of spreading a coating of finely held of force under theaction of which it will be translated to the surface to be coated, and

bonding the finely divided material to the surface be coated.

24. In the manufacture of abrasives, the improved method which consistsin providing a carrier having a surface coated with an adhesive,depositing finely divided abrasive material upon said surface anddispersing the particles by the action of an electrical field as theyare being deposited upon the surface.

25. In the manufacture of abrasives, the improved method which consistsin depositing abrasive. particles'upon a carrier surface, providing anadhesive material for retaining the particles on the carrier, anddispersing the particles by the action of an electrical field as theyare applied to the carrier.

26. In the manufacture of abrasives, the improved method which consistsin providing a carrier having a surface coated with an adhesive,depositing finely divided nonmagnetic abrasive material upon saidsurface and dispersing the particles upon the surface by the action ofan electrical field.

2'7. In the manufacture of abrasives, the improved method whichconsists'in providing a carrier having a surface coated with anadhesive, directing abrasive particles toward said adhesively coatedsurface, and controlling the position of. the particles relative to oneanother on the carrier by an electrical field.

28. In the manufacture of abrasives, the improved method which consistsin providing a carrier having a surface coated with an adhesive,directing abrasive particles toward said adhesively coated surface, andcontrolling the position of-the'partlcles relative to one another intheir path to the carrier and on the carrier by an electrical field.

29. Apparatus for the manufacture of abrasives, comprising means forsupporting a carrier having a surface coated with an adhesive'adapted toreceive and retain abrasive particles. means for supplying abrasiveparticles and directing the same toward said surface, and an electricalfield disposed in the path of said particles so as to control thearrangement of thesame relative to one another at the time they aredeposited upon the carrier.

30. In the manufactureofabrasives the improved method of depositingabrasive particlesupon a carrier surface which includes providing anadhesive material for retaining the particles on the carrier andprojecting the particles substantially longitudinally of their axes bythe action of an electric field as they are applied to the carrier. I

31. In the ,manufacture of abrasives the improved method of depositingparticles upon a carrier surface which includes providing an adhesivematerial for retaining the particles on the carrier, forming asuspension of said abrasive particles in a defined zone, and projectingparticles from said zone onto the carrier by the action of an electricalfield.

32. In the manufacture of abrasives the improved method of depositingparticles upon a carrier which includes providing an adhesive ma terialfor retaining the particleso'n the carrier and projecting the particlesonto the carrier by the action of an electrical field independently ofmechanical pressure.

33. In the manufacture of abrasives, the improved method of depositingparticles upon an adhesive carrier which includes moving the particlesinto adhesive engagement with the carrier in spaced relationship to eachother the deposition being effected under the influence caused bit theaction of electrical force creatin an electrical field affecting thespaced relationship of the adhesive carrier which includes moving theparticles into adhesive engagement with the carrier in substantially asingle layer the deposition being effected under the influence caused bythe action of electric force creating an electrical field affecting theparticles in the movement aforesaid.

35. In the manufacture of abrasives, the improved method of depositingparticles on an adhesive carrier which consists in moving the particlesinto adhesive relation with the carrier, the deposition being effectedunder the influence caused by the action of electricforce creating anelectrical field affecting the particles in the movement aforesaid.

36. In the manufacture of abrasives, the improved method of depositingparticles of elongated character thereby having different degrees ofeffective cutting portions upon a carrier which includes providing anadhesive material for retaining the particles on the carrier andprojecting the particles onto the carrier, the deposition being effectedunder the influence caused by the action of an electrical field actingperpendicular to the surface of the carrier whereby they are depositedon the carrier with their major effective cutting portions in thedirection of the electrical field.

37. In the manufacture of abrasives, the improved method of depositingthe abrasive particles upon a carrier surface which includes providingan adhesive material for retaining the particles on the carrier andprojecting the parcarrier which includes providing an adhesive materialfor retaining the particles on the carrier and projecting the particlesonto the carrier by the action of an electrical field and controllingthe quantity of the particles deposited on the carrier by variation inthe quantity of the particles brought within the electrical field.

39. In the art of making flexible abrasives, the provision of acontinuously flexible carrier web. applying a hardenable adhesivematerial to said carrier web, progressively feeding said carrier webwhile the adhesive is soft and receptive into the presence or a supplyof pulverulent abrading material. activating the abrading material ad-Jacent to the carrier to form an extended arrangement of particles, andimpressing an electrlcal fleld on such activated abrasive material formoving it onto the carrier with the major portion of the individualparticles thereof having their longitudinal axes substantiallyperpendicular to the carrier web.

40. In the art of making flexible abrasives, the provision of acontinuously flexible carrier web, applying a hardenable adhesivematerial to said carrier web, progressively feeding said carrier webwhile the adhesive is soft and receptive into the presence of a supplyof pulverulent abrading material, activating the abrading materialadjacent to the carrier to form an extended arrangement of particles,directing the thus activated particles into a predetermined zoneadjacent to said carrier web, and impressing an electrical field on thethus activated abrasive particles for moving them into intimate adhesiveengagement with the carrier web.

41. In the manufacture of abrasives, the improved method which consistsin providing a carrier having a surface coated with an adhesive,depositing finely divided abrasive material upon said surface by anelectrical field, the particles being thereby held apart andconsequently more effectively distributed as they are deposited uponsaid surface carrying said adhesive.

42. In the manufacture of abrasives, the improved method which consistsin providing a carrier having a surface coated with an adhesive, coatingthe adhesive surface with the abrasive by passing the abrasive particlesto the carrier and holding them apart by an electrical field wherebythey are projected onto the carrier in spaced relationship relatively toeach other.

43. An apparatus for the manufacture of coated carriers comprising meansfor supplying a controlled feed of finely divided solid material adaptedto be dispersed by an electrical field, means for supporting anadhesively surfaced carrier to be coated, and means for producing anelectrical field to disperse the individual particles of finely dividedmaterial upon said adhesive surface as the material is supplied thereto.

44. An apparatus for the manufacture of coated carriers comprising meansfor supplying a controlled feed of finely divided solid material adaptedto be dispersed by an electrical field, means for supporting andcausing-to travel adjacent said supply means an adhesively surfacedcarrier to be coated, and means for producing an electrical field todisperse the individual particles of finely divided material upon saidadhesive surface as the material is supplied thereto.

45. In the manufacture of abrasives, the improved method which consistsin providing a carrier having a surface coated with an adhesive,depositing finely divided abrasive material upon said surface andthrough the medium of an'electricai field controlling the arrangement ofthe abrasive particles on the adhesive surface to cause the same to besubstantially uniformly oriented with their major axes at substantiallyright angles to the adhesively coated carrier surface. V 46. The processof making abrasive material hich includes the step of depositingabrasive particles upon an adhesively coated backing, dispersing theindividual particles and orienting them with major effectiveness forabrasively coating said backing by means of an electrical field.

47. The process of making-abrasive material which includes the step ofdepositing abrasive particles upon an adhesively coated backing,dispersing and holding the individual particles apart wherebyorientation thereof is accomplished with major effectiveness forabrasively coating said backing by means of an electrical field.

48. That step in the manufacture of abrasives to adhesively unite thabrasive to a carrier which comprises depositing finely divided abrasivematerial upon a carrier and through the medium of an electrical fieldcontrolling the arrangement of the abrasive particles on the carrier tocause the same to be substantially uniformly oriented with their majoraxes at substantially right angles to the carrier.

49. In the manufacture of abrasive including proved method whichconsists in providing a carrier, directing abrasive particles towardsaid car-'- rier, controlling the position of the particles. I relativeto one another in their path to the carrier by an electrostatic fieldand varying the relative positions of the particles in said path byadjusting the electrical field to such a value as to electrostaticallypropel the particles as desired.

51. A method of applying a finish to an are ticle of manufacture,consisting in producing a uni-directional current of high voltage in anatmosphere, introducing a coating material in a finely divided form intothe atmosphere, and subjecting the article of manufacture to be coatedto the current and the atmosphere for a predetermined period of time tocause electrical deposition of the material upon the article ofmanufacture.

52. A method of applying a finishjo an article of manufacture,consisting in enclosing a space of predetermined size, introducing intothe enclosed atmosphere a coating material in a finely divided form,conveying the article of manufacture to be coated through the enclosedatmosphere, and subjecting the article of manufacture and the coatingmaterial to a difference of electrical potential to cause, the coatingmaterial to be deposited on the article of manufacture.

53. The method of making sandpaper and other products coated withelongated particles which comprises separating elongated particles intoa separated and temporarily suspended condition from a bulk source ofsupply by a force applied to said particles fed from said source,

then ilntroducing the particles so separated and suspended into aposition between an impelling force comprising an electrical fieldand anadhesive coated backing, the particles thereby being presented into theposition aforesaid to permit the particles to alter their position inrespect of each other and then causing the particles to adheresubstantially normally to the backing by the application of theelectrical impelling force to said particles so introduced in the'condition aforesaid.

54. The new article of manufacture comprising apparatus for forming acoating of abrasive and other pulverulent elongated particles upon anadhesively coated surface which includes, in combination, a hopper forsaid particles, and means acting upon the particles fed from said hoppercausing the particles to be arranged in a separated and temporarilysuspended condition, said means including additional means directingsaid particles towards said surface and which confines the movement ofthe particles within a zone ineffective alone to coat the surfacetowards which said particles have been directed by said means, andcomprising an electrical field for impelling said particles from saidzone against said adhesively coated surface to cause adhesion of saidparticles substantially normally to said surface.

55. The method of coating, with finely divided material, an articlewhich is electrically conductive and has a mechanically adhesive surfacecomprising establishing an electrostatic field of force between twoelectrodes of opposite polarity, one of which is in electrical contactwith the surface to be coated, introducing finely divided material intothe electrostatic field of force under the action of which it will betranslated to the surface to be coated and subjecting the surface to thecombined action of the electrostatic field of force and the finelydivided material for sufflcient time to enable it to be-subs'tantiallyuniformly coated.

56. In the manufacture of an article having a coated surface, theimproved method which consists in providing a carrier with an adhesivesurface, introducing into the region of the adhesive surface, a finelydivided coating material, depositing and arranging the finely dividedcoating material upon the adhesive surface by the action of anelectrical field.

57. In the manufacture of articles having coated surfaces, the improvedmethod of arranging finely divided material upon a surface which ismechanically adhesive, which comprises establishing an electrical fieldbetween electrodes of opposite polarity, disposing the surface to becoated within said field, introducing into the region of the adhesivesurface a finely divided coating material, and projecting by means ofthe field against the surface the particles substantially longitudinallyof their axes.

58. The method of applying a finish to an article of maufacture,consisting in producing an electrical field of high voltage in anatmosphere, introducing a coating material in a finely divided form intothe atmosphere and subjecting the article of manufacture to be coated tothe electrical field and the atmosphere for a predetermined period oftime to cause electrical deposition and arrangement of the material uponthe article of manufacture.

59. The method of applying a finish to an article of manufacture,consisting in enclosing a space of predetermined size, introducing intothe enclosed atmosphere a coating material in a line- 1y divided form,subjecting the article of manufacture to be coated to the enclosedatmosphere, and subjecting the article of manufacture and the coatingmaterial to a difference of electrical potential to cause the coatingmaterial to be deposited on the article of manufacture.

JAMES S. SMYSER.

